Known electronic connectors are unable to maintain good conductivity between circuit boards when circuit boards are repeatedly inserted and removed from a computer. Known connectors are unstable and liable to be loosened, distorted or damaged in use.
FIG. 1 shows base platform A having a plurality of conductors B in place on the base platform. Circuit board C is obliquely inserted into groove Al of base platform A having conductors B positioned thereon. Insertion of circuit board C requires little effort. When circuit board C is fixed in upright position, perpendicular to the upper face of the base platform, the vertical fixation of the circuit board depends mainly on fixation mountings A2 which project upwardly from both ends of the base platform. Leaf springs A3 are installed slightly inward of fixation mountings A2. Fixation mountings A2 are molded together with base platform A, in one piece, by injection molding.
Bevel guide block A4 projects inwardly from an inward side of an upper edge of leaf spring A3. When circuit board C receives a force to move it to a vertical position from its slanted position, leaf springs A3 and bevel guide blocks A4 of leaf springs A3 are pushed aside until the circuit board reaches the fixed vertical position. To reach the fixed vertical position, circuit board C is pushed just past two bevel guide blocks A4. Leaf springs A3 are then restored to their original position by the resilience of the material used for the leaf springs. However, although circuit board C is fixed in a vertical position, it can bend and tilt as it receives force from conductors B. Bevel guide blocks A4 engage and support circuit board C in its upright position. Circuit board C and conductors B can be closely engaged to ensure good conductivity. In practical applications, retrieving and inserting an electronic circuit board is complicated, time consuming and must be done frequently.
To remove circuit board C from base platform A, leaf springs A3 are removed by hand so that removal of the circuit board is not hindered by bevel guide blocks A4. Then, electronic circuit board C, which has been supported by a full row of conductors B, springs back to the slant position and can be drawn easily from groove A1 of base platform A.
However, this conventional electronic connector (first generation) has defects and is not favored by the electronic industry. Electronic connectors are widely applied to computer equipment which needs to be of highly reliable quality and stability. High temperatures must be sustained and good insulation is essential. Electronic connectors made of L.C.P. (liquid crystal plastic) possess these characteristics. This raw material has great strength in the longitudinal direction of its injection molding but is weaker in the horizontal direction.
An electronic connector must be retrieved and inserted frequently and repetitively. Each time the electronic connector is retrieved and inserted, the leaf spring bends. When leaf spring A3 and base platform A are made of thin plastic material, the leaf springs are too fragile. When a user pushes on leaf springs A to retrieve circuit board C, a screwdriver may sometimes be used to push the leaf spring. In doing so the direction of the pushing force is in the horizontal direction in which the plastic leaf spring is weaker. A screwdriver is used because the space available in a computer is often insufficient for fingers to reach. When excessive force is applied to leaf spring A3, it is easily broken and circuit board C is unable to be maintained in its proper upright position. Circuit board C becomes loose, makes poor contact with conductors B and becomes useless. At that time base platform A must be replaced, which is time consuming and costly.
A second generation product, also of the prior art, is illustrated in FIG. 2. This second generation product was introduced to correct the defects of the first generation electronic connector of FIG. 1. This second generation electronic connector is very different from the first generation product described above. As shown in FIG. 2, leaf spring E, located between the fixed mountings at each end of base platform D, is made of pressed metal which has been formed into a fixed shape. After the pressed metal leaf springs E are shaped, they are inserted into fixed positions, adjacent fixed mounting D1, to lock the circuit board in fixed position. Leaf spring E includes face E1 which is bent backward. Beveled convex face E2 is attached to face E1 at one side. On a lower portion of the opposite side of leaf spring E, bent face E3 extends inward. The sheet body of leaf spring E is bent again in the reverse direction outwardly and upwardly. Thus, leaf spring E is bent into a "U" shape in an attempt to attain the proper degree of resilience. Assembly of leaf spring E with fixation mounting D1 in base platform D requires insertion of a lower part of the "U" shape into the groove of the fixation mounting. FIG. 2-1 shows leaf spring E in fixed position. Side face E3 engages the back of fixation mounting D1.
When a circuit board is inserted from the slant position to an upright position, the beveled convex face E2 of leaf spring E is pushed away until bevel convex face E2 engages and supports the circuit board in its correct position. The substitution of a metal leaf spring for a conventional plastic leaf spring resolves the problem of the easy breakage of the plastic leaf spring and its lack of durability. Although the second generation product is made of satisfactory material and is more convenient in use, defects still exist due to poor design with respect to the structure of leaf spring E and its coordination with fixation mounting D1. These defects include the following problems. Leaf spring E must first be pressed into the required shape and then a further process is required to bend it into a "U" shape. The shape is unduly complex and the processing is time consuming and uneconomical. The "U" shape uses an excessive amount of material in addition to needing costly processing.
Further, as shown in FIG. 2-1, gap X in the rebate within the fixation mounting is very large and allows leaf spring E to move excessively forward or backward when pushed by the user. Movement of leaf spring E is limited to the width of gap X of the rebate. This excessive movement produces metal fatigue in the "U" shaped portion of leaf spring E. Once metal fatigue appears, the resilience of leaf spring E deteriorates and its stability in clamping the circuit board likewise deteriorates. Ultimately, the circuit board loosens and contact is reduced.
Moreover, when the circuit board is pushed into the vertical position against leaf spring E, leaf spring E is also pushed. Leaf spring E receives longitudinal and horizontal forces and also simultaneously receives a component of force in the oblique direction (approaching 45.degree.) as a result of the support between the circuit board and slant convex face E2 of leaf spring E. Thus, the face at the rear side of leaf spring E is inserted and secured in the groove of the fixation mount D1. The sheet body at the front side, adjacent slant convex face E2, is pushed and supported in an oblique direction so that the sheet body at the front side and the sheet body at the rear side bend and are distorted in oblique directions at opposite positions. After such frequent distortions, leaf spring E is permanently twisted and the fixation of the circuit board is adversely affected. The circuit board may be loosened and displaced, adversely affecting its contact and conductivity with the leaf spring.